1. Field of the Invention
This invention relates generally to the use of remotely operated vehicles (ROV) in conjunction with systems and apparatus for underwater work activity, and more particularly to a system incorporating a submersible vessel and an ROV for deep sea bottom work and repair activity particularly associated with oil and gas well conduit resting on the sea bottom, the vessel also referred to herein as “Sub-Cat”.
2. Description of Related Art
A number of systems and apparatus have been developed for shallow and deep water work and repair activity required to install, maintain and repair deep water equipment such as oil and gas well fields.
U.S. Pat. No. 4,052,703 to Collins, Sr., et al. discloses a sub sea well installation having means for performing control functions by electrical command signals transmitted over a primary cable from a remote surface location. An apparatus and method of transferring seismic equipment to and from an operations platform and an underwater location are disclosed by Thompson et al. in U.S. Publication 2009/0052992.
Thompson also teaches a method and apparatus to deploy and retrieve ocean bottom seismometer systems in deep marine environments in U.S. Publication 2007/0258774. An apparatus for use in servicing a submerged unit is disclosed in U.S. Pat. No. 4,784,525 to Francois.
Entralgo et al. teach a remotely operated system and method for deployment of cables and other lines sub sea in U.S. Publication No. 2005/0276665. A sub sea well workover system and method are taught by Torres in U.S. Publication 2004/0194963.
U.S. Patent Re. 28,978 to Brooks discloses a sub sea system for the recovery of subaqueous deposits of fluid minerals. Chenin teaches a seafloor-surface connection installation for a submarine pipeline in U.S. Publication 2004/0218981.
Taylor, Jr. teaches a drone vessel for a remote operated vehicle in U.S. Pat. No. 6,349,665. A modular watercraft capable of both surface and submersible accommodation and transport of passengers is taught by Marion in U.S. Pat. No. 7,246,566.
U.S. Pat. No. 4,014,180 to Kelly et al. discloses a method for making a remote controlled sub sea pipe connection. Pado teaches a remotely operated underwater vehicle in U.S. Pat. No. 4,721,055. A method and apparatus for installing underwater flowlines is taught by Ames in U.S. Pat. No. 4,075,862.
Willums teaches a method and apparatus for underwater hydraulic conveying in U.S. Pat. No. 4,030,216. A system and vessel for supporting offshore fields is taught by Crossley et al. in U.S. Publication 2008/0210432.
Haughom discloses a drilling rig placed on the seabed and equipped for drilling of oil and gas wells in U.S. Publication 2007/0196180. Bhat et al. teach a dry tree subsea well communications methods using variable tension large offset risers in U.S. Publication 2007/0107905.
A subsea structure load monitoring and control system is disclosed by McCoy, Jr. in U.S. Publication 2009/0056936. Rytlewski et al. teach a method and system of subsea intervention in U.S. Publication 2002/0040782.
In U.S. Publication 2006/0159524, Thompson et al. disclose a method and apparatus for deployment of ocean bottom seismometers. A remotely operated vehicle retrievable sea floor pump is taught by Ireland et al. in U.S. Publication 2005/0016735.
Askeland discloses a system and method for well intervention in U.S. Publication 2008/0230228. U.S. Pat. No. 6,588,985 to Bernard discloses an apparatus and method for deploying an object or a load on a seabed.
Weather conditions at the surface of the water can also have an impact upon the ability to implement work and repair activity. Moreover, travel to the work site area may require substantial amounts of fuel and time to transport the primary support vehicle which, if of sufficient size to withstand the rigors of heavy seas from severe weather conditions, will also demand more travel time and fuel consumption.
The present invention provides a system which includes a primary vessel capable of high speed travel to arrive at a work site area quickly and which carries an ROV launch cage capable of being submerged to great depths before the ROV it carries is deployed from the launch cage. Should heavy seas or severe weather conditions be present at the work site, the vessel is capable of being submerged to shallow water depths sufficient to be relatively unaffected by those sea surface conditions (e.g., up to about 200′ depth). However, a surface power buoy in those circumstances is deployable at the surface to maintain radio RF contact with other ships and shore stations and to continue to receive GPS positioning signals which are transmitted via a first umbilical cord to the manned vessel for onsite operations control. By deploying the ROV from the launch cage, the ROV umbilical cord need not be of great length as the launch cage may be deployed to great depths before launch of the ROV to conduct work activities on and near the sea bottom.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those skilled in the art upon a reading of the specification and a study of the drawings.